Transesophageal Echocardiography for Congenital Heart Disease in the Adult
Pablo Motta
Carolyn L. Taylor
Wanda C. Miller-Hance
INTRODUCTION
Advances in medical and surgical care over the last several decades have increased survival rates and dramatically extended life expectancy in all forms of congenital heart disease (CHD). This progress has contributed to a changing population of affected individuals, in fact, it is well recognized that at the current time adults with CHD outnumber children. This is even the case for the most critical defects. As such, CHD is no longer considered to represent a disease exclusive to childhood, but a subject of relevance to all those who provide anesthetic care, regardless of patient age.
The spectrum of CHD seen in the adult varies widely. Pathologies range from mild anomalies with no clinical repercussions to extremely complex malformations characterized by the presence of multiple coexistent defects. Echocardiography represents the primary noninvasive imaging modality in the assessment of these malformations and has significantly contributed to improvements in patient care. As technology has evolved, the transesophageal approach has extended the applications of echocardiography by allowing the acquisition of anatomic and functional information in many cases not obtainable by transthoracic imaging. This is of particular benefit to those with suboptimal transthoracic windows as transesophageal echocardiography (TEE) significantly enhances the detailed characterization of congenital defects and the evaluation of hemodynamics. Additional major contributions of TEE in CHD in the intraoperative setting include the assessment of the surgical intervention, detection of residual pathology, and surgical guidance if an immediate revision is warranted. TEE also plays a critical role in the cardiac catheterization and electrophysiology laboratories as an adjunct to therapeutic interventions.
In recent years, three-dimensional TEE (3D-TEE) has been increasingly applied to all forms of heart disease, including congenital pathology. The benefits of the technology in facilitating diagnostic and therapeutic strategies in patients with CHD have been well demonstrated and continue to evolve.
This chapter reviews relevant aspects of adult CHD with corresponding applications of TEE. The role of this imaging modality in the intraoperative and cardiac catheterization settings is highlighted. For the purposes of this review, in terms of suggested TEE imaging planes, we focus on the more common anatomic arrangement of situs solitus and levocardia for each of the defects. Although many of the congenital cardiovascular malformations can be characterized using the standard TEE views recommended by the Society of Cardiovascular Anesthesiologists (SCA) and American Society of Echocardiography (ASE) in the comprehensive guidelines, in some cases the detailed examination of congenital lesions and associated hemodynamic perturbations, particularly in the presence of complex disease and abnormal cardiac positions, requires alternative or modified planes of interrogation. This is outlined in the recently published guidelines on the comprehensive TEE evaluation in CHD (refer to the corresponding section later this chapter). As relevant to the pathology being considered, these modified cross-sections/sweeps will be described. The 3D-TEE experience in the adult patient with CHD will also be addressed.
INCIDENCE OF CONGENITAL HEART DISEASE AND PREVALENCE IN THE ADULT POPULATION
CHD represents the most common major congenital malformation occurring in approximately 1% of live births worldwide. This figure does not include the bicuspid aortic valve (Bic AV), occurring in 2% to 3% of the general population. At birth, the most common lesion is that of a ventricular septal defect (VSD). Other relatively common congenital pathologies include atrial septal defects (ASDs), pulmonary (pulmonic) stenosis (PS), and persistent patency of the ductus arteriosus (PDA). Beyond these defects, other less prevalent pathologies include tetralogy of Fallot (TOF), aortic stenosis (AS), coarctation of the aorta (CoA), atrioventricular septal defect (AVSD), and transposition of the great arteries (TGA) (refer to Table 19.1).
Not surprisingly, the highest survival rate in CHD occurs among infants with milder forms of disease. However, overall outcome in those with complex pathologies has improved dramatically over the last several
decades. This is attributed to factors such as prenatal diagnosis, advances in medical and surgical strategies, definitive surgical repair at an earlier age, and improvements in intraoperative/postoperative management.
decades. This is attributed to factors such as prenatal diagnosis, advances in medical and surgical strategies, definitive surgical repair at an earlier age, and improvements in intraoperative/postoperative management.
TABLE 19.1 Congenital Heart Disease in the Adult: Physiology, Epidemiology, Associated Pathology, Treatment and Prognosis | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
The prevalence of CHD is estimated at approximately 4 per 1,000 living adults, of which nearly 10% have complex CHD. In the United States this accounts for a population of nearly 2 million adults. This group of patients is referred to as the “adult with CHD (ACHD)” or as the “grown-up with CHD (GUCH)” population. It is anticipated that the number of adults with congenital cardiovascular malformations will continue to increase worldwide, as well as the complexity of this patient group.
CLASSIFICATION OF CONGENITAL HEART DISEASE
In view of the wide spectrum of pathologies in CHD, several classification schemes have been proposed to facilitate our understanding of the defects and their associated physiologic impact. Malformations can be characterized, for example, according to disease severity, presence or absence of cyanosis, or primary physiologic alteration.
Based on Severity of Disease
Defects have been stratified according to their severity or level of complexity into simple, moderate severity, and complex defects. This classification scheme has been utilized for recommendations regarding patient care, estimation of long-term problems, and expectation of potential outcomes. Intracardiac communications in their isolated forms represent in most cases simple defects. Mild PS and a small PDA are also considered simple forms of CHD. Moderate defects include, for example, CoA, TOF, and Ebstein anomaly. Complex pathology includes all forms of cyanotic CHD, lesions associated with multiple concomitant defects, and single ventricles.
Based on the Presence or Absence of Cyanosis
In this scheme, congenital cardiac malformations are classified into acyanotic or cyanotic lesions based on whether the primary functional disorder results in cyanosis. Conditions associated with cyanosis are characterized by restrictive pulmonary blood flow (in the presence of intracardiac shunting) or complete arterial and venous admixture. Cyanosis is less likely to occur in individuals with pulmonary overcirculation secondary to isolated intracardiac communications.
Based on the Physiology of the Defect
This classification algorithm based on the physiologic spectrum of CHD comprises four major categories: shunts, obstructions to either pulmonary or systemic blood flow, regurgitant pathologies, and mixed lesions. Shunt lesions occur at the intracardiac or extracardiac levels. The direction and magnitude of shunting depend on the size of the communication and the relative resistances of the pulmonary and systemic vascular beds. Obstructive lesions can affect the inflow or outflow of blood and vary widely in severity. Regurgitant disease is rarely found in isolation and is frequently secondary to the primary pathology. In mixed lesions, which account for a significant number of cyanotic heart defects, there is mixing of the systemic and pulmonary venous returns.
GUIDELINES FOR TRANSESOPHAGEAL ECHOCARDIOGRAPHY IN CONGENITAL HEART DISEASE
Guidelines for comprehensive TEE imaging in CHD as recommended by the ASE were the subject of recent work detailing techniques, protocols, and 3D TEE methods in this population. The reader is referred to this publication as an essential reference on the subject.
Key points from the guidelines include:
A suggested imaging protocol that includes 28 two-dimensional (2D) tomographic views. Many of these represent cross sections previously described in the comprehensive TEE guidelines by the SCA/ASE published in 2013, with modifications and additions given the congenital focus of the document, unlike prior guidelines that mainly addressed the adult with a structurally normal heart.
TEE views outlined to be regarded as a foundation given the fact that numerous variants and wide spectrum of abnormalities in CHD frequently necessitate modification of these key views and/or additional nonstandard views.
TEE imaging in CHD to rely on examination of structures rather than previously defined views.
The need not only for single beat recordings in congenital TEE assessment, but also for multiple beat loops and sweeps that display the anatomic and spatial relationships among structures.
Recommendations for the use of a combination of modalities that include 2D imaging and Doppler interrogation (spectral and color flow) in multiple views, in addition to 3D structural and color Doppler imaging, as indicated, in the evaluation of any abnormalities.
Consideration for the use of 3D TEE particularly during: (1) transcatheter closure of septal defects for procedural guidance, measurement of defects, and visualization of hardware; (2) assessment of atrioventricular valves; and (3) evaluation of the left ventricular outflow/aortic valve.
INDICATIONS FOR TRANSESOPHAGEAL ECHOCARDIOGRAPHY IN THE ADULT WITH CONGENITAL HEART DISEASE
The indications for TEE in patients with CHD fall within the major categories of diagnostic use, perioperative assessment, and guidance during procedures in the cardiac catheterization/electrophysiology laboratories. Regardless of the indication for the study, when performing TEE, it is important to review in advance the details of the medical history, particularly as it pertains to the initial anatomy and prior interventions as many adult patients have complex disease. A review of transthoracic studies and any prior TEE images is imperative as this allows an understanding of the anatomy and assists the echocardiographer with regard to what to expect.
TEE for Diagnostic Applications
Transthoracic echocardiography (TTE) can be suboptimal in the adult patient due to poor windows related to obesity, muscle mass, or prior cardiothoracic interventions. This is in contrast to children where TTE is diagnostic in most cases and only in a few instances are additional studies required. Particularly in the adult congenital population, TEE plays an important diagnostic role. The transesophageal imaging approach may also be superior in the evaluation of certain pathologies such as endocarditis and aortic root abscess, for exclusion of intracardiac thrombus prior to cardioversion or to identify embolic source, for assessment of small intracardiac communications, anomalous pulmonary venous connections, aortic root/ascending aorta (Asc Ao) pathology, after complex interventions such as intracardiac baffles and Fontan procedures, conduits, and prosthetic heart valves.
TEE During Cardiothoracic Surgery
Imaging during cardiac surgery represents the most common indication for TEE in CHD. An extensive experience has documented the ability of intraoperative imaging to improve the quality of the surgical interventions in these patients. As such, TEE has become standard of care in centers that specialize in CHD, in agreement with the indications outlined by various clinical practice guidelines.
Intraoperative imaging provides detailed anatomic and hemodynamic information prior to the planned surgical procedure and assists in the assessment of the quality of the repair. A major impact, considered when unique prebypass TEE information alters the planned surgical intervention in CHD or postbypass TEE prompts immediate revision of hemodynamically significant defects, has been reported in ˜14% of cases. This is more likely to occur in younger patients with CHD, during reoperations, and in those undergoing valve repairs and complex outflow tract reconstructions. Among institutions that routinely utilize intraoperative imaging during surgery for CHD, the return to bypass rate as guided by TEE is reported to be in the range of approximately 3% to 7%. Failure to address significant residual pathology has been associated with high morbidity in this population and in some cases accounts for perioperative mortality. Additional benefits of intraoperative TEE in patients with CHD include the recognition of complications associated with cannulation during cardiopulmonary bypass, detection of intracardiac air and ensuring adequate cardiac deairing, assessment of ventricular loading conditions and myocardial performance, detection of myocardial ischemia, and identification of problems associated with weaning from bypass.
Over the last several years, the applications of 3D-TEE have been extended to a variety of congenital pathologies including septal defects, valvar lesions, outflow tracts, and complex abnormalities of cardiac connections. The additional diagnostic information provided by the 3D technology has been shown to enhance 2D data in clinical decision-making.
TEE in the Cardiac Catheterization/Electrophysiology Laboratory
The most common indications for catheter-based interventions in the ACHD are: valvular disease, closure of communications (intracardiac/vascular), and relief of vascular obstruction. The use of TEE is well documented in these patients. Benefits include the acquisition of detailed anatomic and hemodynamic data before and during interventions, guidance by real-time evaluation of catheter placement across valves and vessels, immediate assessment of the results, and monitoring for catheter-related complications. Transesophageal imaging can also facilitate transseptal puncture and catheter manipulation in the electrophysiology laboratory. As the applications of 3D-TEE continue to evolve, this technology is likely to provide further benefits to the care of patients with CHD undergoing catheter-based interventions by enhancing the characterization of the defects and providing guidance and monitoring during the procedures.
SELECTED CONGENITAL HEART DEFECTS
The section that follows provides an overview of selected congenital heart defects. A brief discussion of anatomy, pathophysiology, and management is presented followed by the detailed TEE evaluation of each anomaly. This information is summarized in Tables 19.1 and 19.2.
ATRIAL SEPTAL DEFECT
Anatomy
Defects that result in atrial level shunting are termed ASDs. This may not necessarily imply a deficiency of the atrial septum itself. An overview of the embryological processes involved in atrial septation, as depicted in Fig. 19.1, facilitates our understanding of atrial septal anatomy and atrial communications that persists after septation. Four main types of ASDs include: ostium secundum, ostium primum, sinus venosus, and coronary sinus defects (Fig. 19.2A). ASDs account for approximately 30% of all cases of CHD detected in adults and in general are more common in females.
Ostium secundum defects are commonly located in the central portion of the interatrial septum in the region of the fossa ovalis and account for 70% of all atrial communications. Associated abnormalities include mitral valve prolapse and mitral regurgitation.
Ostium primum defects (also known as partial AVSDs) are located in the inferior aspect of the interatrial septum. They account for approximately 20% of ASDs and are associated with a cleft in the anterior mitral leaflet and mitral regurgitation. This defect is considered within the spectrum of AVSDs and can be seen in patients with Down syndrome, although the complete form of the defect is the more common pathology.
Sinus venosus defects occur posteriorly, adjacent to the entrance of the superior vena cava (SVC) or inferior vena cava (IVC) into the RA. The superior defect is the most common type. They account for 5% to 10% of ASDs. In this lesion, straddling of the caval vein over the interatrial septum is commonly seen. These defects are often associated with partial anomalous pulmonary venous drainage from the right lung due to deficiency of the wall that normally separates the veins and LA leading to pulmonary vein unroofing.
Coronary sinus defects result from a communication between the coronary sinus (coronary sinus septum) and the LA. These defects are relatively rare (less than 2% of ASDs) and frequently occur in association with other malformations. They are typically seen within the context of a persistent L-SVC draining to an unroofed coronary sinus. In this setting the orifice of the coronary sinus is usually large.
Pathophysiology
The physiologic consequence of an ASD is determined by the degree of shunting (predominant direction is usually left-to-right; Fig. 19.2B). The size of the defect, ventricular compliances, and PA pressures determine the magnitude of the shunt. A large defect leading to pulmonary overcirculation results in right-sided diastolic volume overload manifested as RA, right ventricular (RV), and PA dilation. Over time atrial arrhythmias and heart failure can develop. Mild to moderate elevations of PA pressure can be seen in older patients, however severe pulmonary hypertension rarely occurs. Adults can remain asymptomatic and an ASD may represent an incidental finding on echocardiography.
 FIGURE 19.1 Stages of atrial septation. A: Atrial septation begins as early as the fifth week of gestation. As the septum primum grows inferiorly toward the endocardial cushions, the ostium secundum, labeled as perforations in upper septum primum, forms in the posterior portion of the septum primum. Once the ostium secundum is formed it ensures the flow of blood across the atrial septum in the fetus. Thereafter, the septum primum completes its growth and becomes continuous with the developing endocardial cushions of the atrioventricular junction (see arrows). B: The septum secundum develops parallel and to the right of the septum primum. It forms an incomplete partition. C: The remaining opening in the septum secundum is known as the foramen ovale. It is covered by a flap valve formed from tissue from the septum primum. Normally this flap valve closes when pressure in the left atrium increases, exceeding right atrial pressure, after birth. |
Management
Most patients with large defects undergo surgical closure. Selected ostium secundum defects may be amenable to percutaneous closure in the cardiac catheterization laboratory. Suitability for transcatheter device occlusion of secundum ASDs includes size of the defect and the presence of adequate rims of surrounding atrial septal tissue. Transcatheter device closure is also considered in the patient with a PFO and a history of a cerebrovascular event in order to alter the risk of potential paradoxical emboli. Device closure of other types of interatrial communications is not feasible due to the presence of critically important structures surrounding the defects that may be compromised by the occluder.
 FIGURE 19.2 Atrial septal defects. A: The illustration depicts the typical location of the various interatrial communication as follows: centrally located ostium secundum defect, inferiorly located ostium primum defect, sinus venosus defect, near the entrance of either the superior vena cava (SVC) or inferior vena cava (IVC) and frequently associated with anomalous pulmonary venous drainage, and coronary sinus defect. RA, right atrium; RV, right ventricle. B: The graphic displays a secundum-type atrial septal defect, the arrow showing the usual direction of shunting, from left-to-right across the interatrial communication. (Printed with permission from Texas Children’s Hospital.) |
Transesophageal Echocardiographic Evaluation
The echocardiographic evaluation of the interatrial septum and atrial septal communications should follow established guidelines specifically developed for this assessment. Suggested cross-sections for a focused examination of a secundum ASD: midesophageal (ME) four-chamber (4 CH) (Fig. 19.3, 
Video 19.1), ME bicaval, ME AV short-axis (SAX), ME RV inflow-outflow (in-out), and deep transgastric (TG) atrial septal views (equivalent to ME bicaval view, obtained at ˜90°). The region of the fossa ovalis and the flap of a PFO can be optimally imaged from the ME bicaval view. Additional cross-sections may be relevant in the assessment of other atrial level communications and their frequently associated pathology. In the case a primum
ASD, the ME 4 CH view is diagnostic (Fig. 19.4,
Video 19.2), other useful views include the ME two-chamber (2 CH), ME long-axis (LAX), and TG basal SAX views (for cleft mitral valve); for a sinus venosus defect, the ME bicaval view is particularly helpful (Fig. 19.5, 
Video 19.3) and cross-sections that allow for imaging of the pulmonary veins (ME right pulmonary veins and ME left pulmonary veins); for a coronary sinus defect, views that examine the coronary sinus (ME 4 CH with retroflexion; Fig. 19.6A, 
Video 19.4) and those that allow for imaging of an associated L-SVC (sweep obtained by rotating probe leftward in the upper esophageal aortic arch [UE Ao Arch] SAX view).
Video 19.1), ME bicaval, ME AV short-axis (SAX), ME RV inflow-outflow (in-out), and deep transgastric (TG) atrial septal views (equivalent to ME bicaval view, obtained at ˜90°). The region of the fossa ovalis and the flap of a PFO can be optimally imaged from the ME bicaval view. Additional cross-sections may be relevant in the assessment of other atrial level communications and their frequently associated pathology. In the case a primum ASD, the ME 4 CH view is diagnostic (Fig. 19.4,
Video 19.2), other useful views include the ME two-chamber (2 CH), ME long-axis (LAX), and TG basal SAX views (for cleft mitral valve); for a sinus venosus defect, the ME bicaval view is particularly helpful (Fig. 19.5, Video 19.3) and cross-sections that allow for imaging of the pulmonary veins (ME right pulmonary veins and ME left pulmonary veins); for a coronary sinus defect, views that examine the coronary sinus (ME 4 CH with retroflexion; Fig. 19.6A, Video 19.4) and those that allow for imaging of an associated L-SVC (sweep obtained by rotating probe leftward in the upper esophageal aortic arch [UE Ao Arch] SAX view). FIGURE 19.3 Secundum atrial septal defect. A: Midesophageal four-chamber view showing a moderate size central defect in the atrial septum (arrow), typical of a secundum atrial septal defect. B: Corresponding color Doppler demonstrating left-to-right atrial level shunting (blue flow). LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. |
 FIGURE 19.4 Primum atrial septal defect. A: Midesophageal four-chamber view depicting a relatively small defect in the inferior aspect of the atrial septum (arrow), location characteristic of a primum atrial septal defect. B: Corresponding color flow Doppler demonstrating left-to-right atrial level shunting. An aneurysm, also known as a tricuspid pouch, is seen billowing into the right ventricle (RV) representing remnants of endocardial cushion tissue. LA, left atrium; LV, left ventricle; RA, right atrium. |
 FIGURE 19.5 Sinus venosus atrial septal defect. A: Midesophageal bicaval view depicting a communication in the interatrial septum near the entrance of the superior vena cava (arrow). The findings are typical of a superior vena cava-type sinus venosus atrial septal defect. B: Corresponding color flow mapping demonstrating left-to-right atrial level shunting across the communication. The superior vena cava frequently overrides this type of defect, which is usually associated with anomalous pulmonary venous drainage. LA, left atrium; RA, right atrium. |
 FIGURE 19.6 Dilated coronary sinus associated with a persistent left superior vena cava. A: Midesophageal four-chamber view with TEE probe retroflexion showing a dilated coronary sinus (white arrow). B: Same view obtained after injection of agitated saline into a left arm vein displaying contrast in the coronary sinus and right atrium and confirming the presence of a persistent left superior vena cava connection draining into the coronary sinus. No contrast is seen in the left atrium, excluding unroofing of the coronary sinus. |
Goals of the Two-Dimensional Examination
Definition of defect type, location, size, shape, number of orifices. Detection of a PFO or small interatrial communication may require the intravenous injection of agitated saline or other contrast material and a Valsalva maneuver (or equivalent) in order to increase RA pressure over LA pressure and identify right-to-left shunting
Evaluation of the entire atrial septum. Determination of defect size(s) and rims to assess suitability for transcatheter closure
Anterosuperior (aortic rim): ME AV SAX view, distance between aortic ring and defect (lack of rim does not preclude device deployment)
Posterior: ME 4 CH view, gap between coronary sinus and defect
Inferoanterior: ME 4 CH, space between the defect and atrioventricular valves
Superior-posterior: ME bicaval view, distance between the SVC and defect
Inferoposterior: ME bicaval view, gap between the IVC and defect (deficient rim unfavorable)
Assessment of mitral valve anatomy (evaluate for prolapse/cleft: prolapse may occur in association with secundum ASDs; a cleft in the anterior leaflet is commonly seen in partial AVSD)
Evaluation of pulmonary venous drainage (all cases, but particularly, sinus venosus ASD)
Examination of right-sided structures for dilation and motion of interventricular septum (flattened or paradoxical motion related to volume load)
Contrast echocardiography may be useful in assessing the presence of a persistent L-SVC to coronary sinus communication (Fig. 19.6B,
Video 19.4) and in confirming or excluding unroofing of the coronary sinus in coronary sinus ASD
Evaluation of RV wall thickness, suggestive of pulmonary hypertension
Assessment of ventricular function
Goals of the Doppler Examination
Assessment of flow across defect: nature, direction, and mean velocity
Detection of atrioventricular/semilunar valve regurgitation
Measurement of tricuspid regurgitant jet velocity (VTR) for estimation of PA systolic pressure as follows:
RV systolic pressure = 4 (VTR)2 + RA pressure
In the absence of RV outflow obstruction:
PA systolic pressure = RV systolic pressure (assumes no RV outflow obstruction)
FIGURE 19.7 Postoperative patch closure of secundum atrial septal defect. A: Midesophageal four-chamber view depicting an autologous pericardial patch in the interatrial septum; B: Contrast injection into an arm vein using an agitated mixture of saline and blood showing enhancement of right-sided structures and no contrast in the left heart. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle.
Interrogation of pulmonary venous flows to determine drainage
Estimation of shunt magnitude (pulmonary and systemic blood flows) in the absence of significant atrioventricular valve regurgitation
Goals of the Examination After Surgery
Detection of residual interatrial shunting (color Doppler and contrast echocardiography) (Fig. 19.7,
Video 19.5)
Evaluation of atrioventricular valve competence
Examination of systemic and pulmonary venous pathways (depending on the defect and nature of intervention)
Assessment of ventricular function
Goals of the Examination During Transcatheter Intervention
Determination of defect size and tissue margins or rims around the defect to facilitate device selection
Assessment of relation of defect/device to surrounding anatomic structures (Ao, pulmonary veins, vena cavae, atrioventricular valves, coronary sinus)
Measurement of maximal defect diameter (balloon stretch sizing)
Sizing for selection of device and detection of leaks around occluding balloon, if stop-flow technique is used
Live monitoring and guidance during device positioning, deployment, and determination of device stability
Assessment of residual shunting (Fig. 19.8,
Video 19.6)
FIGURE 19.8 Atrial septal defect, occluder device. A: Midesophageal aortic valve short-axis view with rightwards transducer rotation demonstrating an atrial septal defect closure device (gray arrow) straddling the interatrial septum; B: Midesophageal bicaval view (orthogonal cross-section relative to panel A), depicting the device (gray arrow) appropriately placed across the atrial septal defect before deployment. AO, aorta; LA, left atrium; RA, right atrium; RV, right ventricle; SVC, superior vena cava.
FIGURE 19.9 Atrial septal defect, transcatheter closure. A: Three-dimensional TEE image of a secundum atrial septal defect viewed from the right atrial aspect with visible rims in all quadrants; B: Same view displaying the right atrial disc of the occluder device and the delivery cable prior to release.
Evaluation of proper positioning of device (documentation of unobstructed flow in systemic veins and adjacent pulmonary veins and lack of impingement in adjacent structures prior to and following deployment)
Exclusion of complications related to the intervention (for device: embolization, erosion, pericardial effusion)
Applications of Three-Dimensional Imaging
Enhances visualization of the anatomy of the interatrial septum and spatial details of the defect (size, location, number, rims, shape, relationships between defect/device and adjacent anatomic structures). Various acquisition modes can be used (e.g., 3D narrow-sector, zoomed, wide-angled gated)
Allows for en face views and appreciation of changes in the configuration of the defect throughout the cardiac cycle (Fig. 19.9A,
Video 19.7)
Facilitates continuous visualization of hardware and the 3D relations while monitoring device deployment (Fig. 19.9B,
Video 19.7); X-plane imaging provides simultaneous display of the defect and surrounding structures in orthogonal views
Evaluates for appropriate device position and entrapment of septal rims around the occluder
Provides detailed assessment of residual shunts during device placement (Doppler flow analysis with live 3D color)
Allows for characterization of associated anomalies such as mitral valve cleft in an ostium primum ASD (Fig. 19.10,
Video 19.8)
Allows for acquisition of ventricular volumes and ejection fraction
Provides guidance during procedures requiring transseptal puncture
VENTRICULAR SEPTAL DEFECT
Anatomy
VSDs are classified by location into four major groups: perimembranous, muscular, doubly committed outlet, and inlet defects (Fig. 19.11A). They can occur in isolation or as part of complex malformations. An isolated VSD is the most common congenital cardiac pathology diagnosed in infancy. Because 60% of smaller defects close spontaneously and larger defects are usually repaired in childhood, VSDs account for only 10% to 15% of defects observed in adults with CHD.
Perimembranous defects account for approximately 70% of VSDs, involve most or all of the membranous septum, and can extend into the muscular region. Associated findings may include an aneurysm of the membranous septum that is composed of tricuspid valve tissue. On echocardiography this appears as a tissue pouch and often limits shunting across the defect. Potential associated pathologies include a subaortic membrane or AV cusp herniation/prolapse (resulting in aortic regurgitation). A perimembranous VSD can also be seen in the presence of obstruction within the RV cavity related to muscular band hypertrophy, dividing it into two chambers (double-chambered RV).
 FIGURE 19.10 Cleft mitral valve associated with primum atrial septal defect. Transgastric short-axis view displays a cleft in the anterior mitral leaflet by three-dimensional imaging (arrow). |
 FIGURE 19.11 Ventricular septal defects. A: Graphic rendering of the interventricular septum as seen from the right ventricular aspect. Ventricular septal defects are classified by location into four major groups: perimembranous, muscular, doubly committed (subarterial), and inlet defects. Muscular defects can occur anywhere in the trabecular interventricular septum. In this figure, a cusp of the aortic valve can be visualized through the perimembranous defect. B: Illustration showing left-to-right ventricular level shunting (arrow) across a ventricular septal defect. (Printed with permission from Texas Children’s Hospital.) |
Muscular defects are defined by their location in the muscular portion of the ventricular septum. They account for 20% of VSDs, can be isolated or multiple (“Swiss cheese” type) and are often located in the central or apical portion of the trabecular septum. Postmyocardial infarction ventricular septal rupture can also result in a VSD as a rare complication. These may develop within a few days after a transmural myocardial infarction involving the septum and can be hemodynamically significant. Thus, not all muscular defects encountered in adult patients are congenital in nature.
Doubly committed outlet defects (also known as supracristal, subarterial, subpulmonary, infundibular or conal VSDs) are located in the infundibular septum immediately below the pulmonary (pulmonic) valve. They account for 5% of VSDs and are frequently associated with AV prolapse resulting in regurgitation.
Inlet defects account for approximately 5% of VSDs and are located in close proximity to the atrioventricular valves in the posterior or inlet portion of the ventricular septum. These defects predominate in patients with Down syndrome. An associated primum ASD within the context of a common atrioventricular valve annulus is part of the defect known as a complete AVSD (canal defect or endocardial cushion defect). As previously noted, these are also commonly seen in individuals with Down syndrome.
Pathophysiology
The physiologic consequences of a VSD are determined by the size of the defect and the pulmonary vascular resistance. Moderate to large defects are associated with significant left-to-right shunting (Fig. 19.11B), left heart dilation, and symptoms of heart failure. Pulmonary vascular changes can occur leading to severe pulmonary hypertension in the patient with a large, long-standing VSD and substantial pulmonary overcirculation. This in turn can lead to reversal in the direction of the shunt through the defect (right-to-left shunting) and resultant cyanosis. Increased pulmonary vascular resistance secondary to irreversible vascular changes leads to a condition known as Eisenmenger syndrome, seen rarely today in developed countries. The affected adult has early mortality and is not considered a candidate for surgical repair.
Management
Most symptomatic patients with a VSD require intervention. Surgical closure of an isolated defect is most frequently accomplished through a transatrial or transpulmonary approach. Thus, the location of the communication has important implications for surgical access to the defect. In selected cases transcatheter device occlusion can be an option. This has been more commonly applied to muscular communications due to the distant anatomic relationship of this type of defect to the atrioventricular valves/outflow tracts. In addition, these types of defects (particularly if multiple) can present significant challenges for surgical closure. In some cases, perimembranous defects may be amenable to device closure. A catheter-based intervention can be accomplished either percutaneously in the cardiac catheterization laboratory (most common setting) or in the operating room using a periventricular hybrid approach. The latter strategy uses a combination of surgical and interventional techniques. During a typical procedure, following a sternotomy, the free wall of the RV is punctured with a needle, a wire is introduced, and a sheath is placed across the wire. TEE guides device placement across the defect. Surgery for associated pathology, if necessary, can then be performed using conventional techniques.
Transesophageal Echocardiographic Evaluation
Suggested cross-sections for a focused examination, depending on the type of defect: ME 4 CH (Figs. 19.12, 19.13, 19.14; 
Videos 19.9-19.11), ME 5 CH, ME AV SAX, ME LAX (Fig. 19.15, Video 19.12), ME RV in-out, TG, and deep TG views 
(Video 19.10).
Videos 19.9-19.11), ME 5 CH, ME AV SAX, ME LAX (Fig. 19.15, Video 19.12), ME RV in-out, TG, and deep TG views (Video 19.10).Goals of the Two-Dimensional Examination
Assessment of defect(s) location, size, number, and extension (Figs. 19.12, 19.13, 19.14, 19.15,
Videos 19.9-19.12)
Inspection for associated abnormalities, including ventricular septal aneurysm (Fig. 19.12,
Video 19.9)
Evaluation of AV for deformity (herniation or prolapse; Fig. 19.15,
Video 19.12)
FIGURE 19.12 Perimembranous ventricular septal defect. A: Midesophageal four-chamber view depicting a large defect in the membranous region partially covered by aneurysmal tissue (arrow). B: Corresponding color Doppler demonstrating a significant amount of ventricular level left-to-right shunting across the defect. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle.
FIGURE 19.13 Muscular ventricular septal defects. Image displays two muscular ventricular septal defects (VSDs, arrows) as demonstrated in a transgastric left ventricular short-axis cross-section. The larger defect is located in the mid muscular region and a second smaller one is seen at the apex. LV, left ventricle; RV, right ventricle.
FIGURE 19.14 Inlet ventricular septal defect. Midesophageal four-chamber view depicting a large ventricular septal defect (VSD) in the inlet portion of the ventricular septum (arrow). Note that both atrioventricular valves appear to be at the same level in this defect, in contrast to the offset in the normal heart where the tricuspid valve has a more apical insertion into the ventricular septum as compared to the mitral valve. RA, right atrium; LA, left atrium; RV, right ventricle; LV, left ventricle.
FIGURE 19.15 Supracristal (conal, subarterial) ventricular septal defect. A: Midesophageal aortic valve long-axis view demonstrates prolapse of the aortic valve (right coronary cusp; arrow) through a subarterial ventricular septal defect into the right ventricle. B: Systolic frame demonstrating shunting across the ventricular communication. Ao, aorta; LA, left atrium; LV, left ventricle; RVOT, right ventricular outflow tract.
Examination of PAs and left-sided cardiac structures for dilation
Inspection for findings suggestive of pulmonary hypertension (RV wall thickness and configuration of interventricular septum during systole)
Goals of the Doppler Examination
Confirmation of the presence of the defect, evaluation for additional defects
Determination of the nature, magnitude, and direction of shunt flow
Detection of tricuspid and/or aortic regurgitation (color Doppler)
Estimation of PA systolic pressure by:
Tricuspid regurgitant jet peak velocity (VTR)
VSD jet peak velocity (VVSD):
RV systolic pressure = Systolic arterial blood pressure – 4 (VVSD)2
In the absence of RV outflow obstruction:
RV systolic pressure = PA systolic pressure
In the absence of LV outflow obstruction:
Systemic systolic blood pressure = LV systolic pressure
Determination of flow restriction across VSD (high-velocity VSD jet suggests restriction versus lowvelocity flow of a nonrestrictive defect)
Estimation of the magnitude of the shunt (pulmonary to systemic blood flow ratio) in the absence of significant atrioventricular valve regurgitation
Goals of the Examination After Surgery
Detection of residual shunts and evaluation of hemodynamic significance
Determination of potential changes in valvar regurgitation
Assessment of ventricular function
Goals of the Examination During Transcatheter Intervention
Determination of VSD anatomy, size, and relationship to ventricular inflows and outflows
Evaluation of valvar competence
Detection of leaks around the balloon, if balloon sizing performed
Guidance and monitoring during device deployment
Evaluation of device position in septum and relative to surrounding structures (Fig. 19.16,
Video 19.13)
Assessment of leaks across device
Early detection of complications related to device positioning
 FIGURE 19.16 Muscular ventricular septal defect, transcatheter occlusion. A: Midesophageal four-chamber view showing a ventricular septal defect (VSD) occluder device (arrow) between the mid and apical muscular portion of the ventricular septum. B: Transgastric short-axis view displaying the VSD occluder device (arrow) with color flow imaging. LV, left ventricle; RV, right ventricle. |
Applications of Three-Dimensional Imaging
Improved visualization of defect (location, size, number, shape)
Enhanced characterization of structures surrounding defect during transcatheter closureRelated posts:
Full access? Get Clinical Tree
